li-ion batteries and safety · – electrification with li-ion batteries is a global trend. now it...
TRANSCRIPT
Content
1. Introduction to FFI and the Power Group
2. Public founded research
3. Li-ion battery – basics with focus on battery safety
4. Li-ion incidents – some examples
5. Measures to improve safety in a Li-ion installation
6. Final remarks
• Established 1946 • Major defence R&D organisation in Norway
• Staff 716
• Annual turnover 2015: NOK 878 million (EUR 93,1 million/USD 104,5 million)
Norwegian Defence Research Establishment (FFI)
FFIs power group– Main focus area is battery safety
• Supporting the Norwegian Defence and the Norwegian Maritime Authority (NMA)
• SafeLiLife – Safety and Life of Li-ion batteries in maritime vessels
• MoZEES
• The power group – chemical analysis to large scale destructive tests at shooting ranges.
Where it all started
• Battery powered AUV
• Glass fibre Navy vessel
• No loss of crew and vessel due to battery fire
• NAVSEA: SG270-BV-SAF-010
• Propagation test / overcharging by nominell chariging current
In the civilian society– Wh to MWh
kWh Wh
MWh MWh
Foto: Scanpix Foto: VG
Foto: Statkraft Foto: Maritimt magasin
Public funded Research
• SafeLiLife
• MoZEES
• Life and safety for Li-ion batteries in Maritime conditions (SafeLiLife) • Background:
– Electrification with Li-ion batteries is a global trend. Now it is the maritime sector`s turn.
– Safety of Li-ion batteries is an important issue. Based on the large amounts of energy in a 1 MWh maritime battery, it is absolutely vital that safety of the battery system is assured.
– The degradation and ageing of Li-ion batteries could affect the safety performance of batteries as well.
– Knowledge and the ability to predict capacity decay and battery state of health will be vital information to enable safe and long-life operation of marine battery systems
• R Partners: IFE; NTNU, HiST, FFI • Supported by the Norwegian Research Council and Maritime
Industry, ends December 2016
Lithium batteries and Safety
MoZEES – 2016 - 2024 Mobility Zero Emission Energy Systems
The main objective with MoZEES is to be the Center for environmently-friendly Energy research (FME) with the goal to develop new battery and hydrogen materials, components, and technologies for the existing and future transport Applications on road, rail, and sea
Li-ion batteries - a controlled bombe?
• Energy density of TNT 1.86 kWh/litre
• Energy density of advanced batteries 0.350 kWh/litre
• Energy density of chocolate 6.1 kWh/litre
High energy density is not a dangre by it self, but safe and economical use of Li-ion batteries requires knowlegde
Pb Possible hydrogen formation. The electrolyte is H2SO4, corrosive. NiMH Possible hydrogen formation. The electrolyte is KOH, corrosive.
Please keep in mind – the older systems are not harmless
What is an electrical battery
• A unit which transforms chemical energy to electrical energy and heat
• The main components: Anode, Cathode, Electrolyte, Container
• If liquid electrolyte: Separator – prevetion of a short between anode and cathode
• A battery -cells in series or parallel or both series and parallel
• Rechargeable and non-rechargeable
• Different formats, voltages and capasities
load
anions
cations
Electrolyte
Cathode
Anode
Energy density of some batteries
Source: NASA
Properties – always a trade off
Litium ion – historical background
• The first battery developed around 1990-tallet by SONY.
• Graphite - anode, LiCoO2 – Cathode. High Cell voltage, 3.7 V.
• Used in laptops and cell phones, multiple fires.
• The cathode material was less stable than expected
• Triggered a lot of reseach on the cathode material – keep energy density, improve safety
• Cathode (+): Lithium-metal oxside
• Electrolyte: Organic solvent, e g DMC,EC and added LiPF6
• Anode (-) : Carbon most common
• Separator: PE, PP most common
• Current Collector: Al og Cu
Structure of a Li-ion cell
DMC: dimetylkarbonat, EC: Etylenkarbonat
Contribution to heat evolvement
Evolved gases combustion of a common electrolyte
Abuse Response of 18650 Li-Ion Cells with Different Cathodes Using EC:EMC/LiPF6 and EC:PC:DMC/LiPF6 Electrolytes. Rothe, E.P. 19, s-l.: ESC Transactions, 2008, Vol.11, pp.19-41. 10.1149/1.2897969 ARC: Adiabatic reaction calorimeter
Full cells – different cathodes
B Barnett et al., TIAX
Li-ion incidents
BOEING DREAMLINER B787: 3 fires
Root cause: Probably internal short, lots of smoke
Fire due to massive internal shorting
TESLA-S Fire November 2013
Tesla fire – january 2016
Foto: Dagbladet
Fire due to faulty breaker in the charger
The number of Li-ion cells produced pro anno appr 5 billions (2014) The number of incidents due to Li-ion cells divided by the number of cells produced each year is on ppm level
The concequences however can be devastating especially if it is involving lagre battery packs. Safe battery design and robust surrounding systems scaled to handle battery failures are requried
Probability and consequences
Foto: Shutterstock
Description of the causes initiating unwanted reactions in a Li-ion cell
In the case of a collision – what could happen?
collision what happens rescue
shorts
mechanical load on the battery
water heat Fire and explosion
gases
Exposed to external heat source Caused by: Bad choice of battery location: engine room, sun exposure, fire in the vincinity. Concequences: Fast degradation of the battery (capacity and shelf life), battery fire
Charging at too low temperatures
Charging at too low temperatures - formation of Li-needles
Internal shorts and Thermal Runaway (TR)
From the net From the net
Battery on shore Battery on shore
Charging Charging
Control of temperature range
Li-dentrites
• Can be formed during high charging current (fast charging) and charging at too lowe temperatures.
• The mechanism behind the formation is poorly understood.
Dentrite: needle shaped protusions
Consequences of all the listed causes - the cell heats up
Propagation test 2. 4 kWh module – over charge
Measures to improve safety in a Li-ion installation
Battery design to avoid fire propagation
• Choose a suitable Li-ion cell according to the application and safety requirements – Cell chemistry, size and format affect safety – Evaluate the built-in safety mechanisms of the cell (fuses, current interrupt
devices, shut-down separators, pressure valve/weak spots)
• Perform safety tests on cell level to identify worst case events – Heating tests or overcharge tests are suitable – If the safety test results are unacceptable, choose a different cell (e.g.
another cell chemistry or energy content)
• Base the battery module design on the worst case cell behaviour to avoid propagation – Insulating walls between cells – Ducts for ventilated gases – Weak spots – Cooling
• Verify the chosen design with propagation tests
Measures to improve safety in a Li-ion installation Battery safety can be improved by: • Battery design
• Battery management system
• Control of surroundings (battery installation design)
Improved safety properites of Li-ion cells through • Reduction of the electrolyte flamablility (additives)
• Use solid state electrolyte and ionic liquids
• Increase the stability of the electrode materials
– Chemical composition and coating
• Increase the thermal and mechanical stability of the separator
Different types of separator Important for
• Most common is PP/PE or layers of PP-PE-PP – shut down separator where PE melts at 120-130 oC – cell safety.
• PP-PE-PP mechanical stable up to 165 oC (smp PP).
• Other types e g ceramic – asfety increases on the expence of internal resistance
• Mechanical integrity up to 210 oC
PE-separator in a Li-ion cell
S.Audustin, V.D. Hennige, G. Horpel, C,Hying, Desalination 146 (2002)23, Separion brosjyre
Smp PE, PP - Intern report FFI, PP: polypropylen, PE, polyetylen Smp keramiske separator , Sheng Shui Zhang, J Power S 164 (2007)351
Final remarks
Ensure safety in the enitre life cycle
ES
Docking
Sailing
Dayly overhaul
.
Further reading about battery safety
• Open FFI reports • Reports from Fire Protection Research Foundation
– Li-ion batteries hazard and use assessment – Li-ion batteries hazard and use assessment IIB – Hazard assessment of lithium ion battery energy storage systems
• Reports from Dreamliner incidents • All reports above are available at www.ffi.no/batterisikkerhet
(choose Batterisikkerhet) • D. H. Doughty, A.A. Pesaran, Vehicle Battery Safety Roadmap
Guidance, National Renewable Energy Laboratory, available at www.nrel.gov